1. Technical Field
The present disclosure relates to a photoalignment material, a display substrate having an alignment layer formed using the same, and to a method of manufacturing the display substrate. More particularly, the present disclosure relates to a photoalignment material used in a process for manufacturing an alignment layer of a liquid crystal display (LCD) apparatus, a display substrate having an alignment layer formed using the same, and to a method of manufacturing the display substrate.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) panel includes a display substrate having a thin-film transistor (TFT) as a switching element driving a pixel, an opposite substrate facing the display substrate, and a liquid crystal layer interposed between the display substrate and the opposite substrate. The LCD panel displays an image using the light transmittance of liquid crystal that changes according to voltage.
An alignment layer is formed on interior portions of each of the display substrate and the opposite substrate, because it may be difficult to obtain an ideal liquid crystal molecular arrangement by simply disposing the liquid crystal material between the display substrate and the opposite substrate. The alignment layer may be formed by spreading an alignment raw material using a printing roller of an alignment layer printing apparatus on a base substrate and a rubbing process. For example, the alignment raw material may be a solution including a polyimide polymer.
Static electricity may be generated by rubbing using a rubbing cloth in the rubbing process to form the alignment layer, and thus the display substrate may be damaged by the static electricity. Moreover, the display substrate may be readily polluted in the rubbing process and stained with spots and stains, so that display quality may be decreased. To prevent the static electricity and improve the display quality, a photoalignment process has been developed, wherein the process may include spreading a photoalignment material on the base substrate and photodegrading, photoisomerizing or photopolymerizing the photoalignment material using light.
An alignment layer formed by a method using photoisomerization may have low alignment stability as the orientation of the alignment layer may not be maintained for a long period of time. Furthermore, the alignment layer formed by a method using photoisomerization may have a low photosensitivity compared to an alignment layer formed by a method using photodegradation or photopolymerization. Thus, developing a photoalignment material having a photoreactive portion may be required. However, developing a new photoalignment material may involve high costs. Furthermore, optimizing characteristics of an alignment layer, for example, electro-optical characteristics and manufacturing characteristics, may be difficult.